package org.bouncycastle.pqc.crypto.util;

import java.io.IOException;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1Set;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.pqc.asn1.CMCEPrivateKey;
import org.bouncycastle.pqc.asn1.CMCEPublicKey;
import org.bouncycastle.pqc.asn1.FalconPrivateKey;
import org.bouncycastle.pqc.asn1.FalconPublicKey;
import org.bouncycastle.pqc.asn1.PQCObjectIdentifiers;
import org.bouncycastle.pqc.asn1.SPHINCS256KeyParams;
import org.bouncycastle.pqc.legacy.bike.BIKEPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.cmce.CMCEPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.crystals.dilithium.DilithiumPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.crystals.dilithium.DilithiumPublicKeyParameters;
import org.bouncycastle.pqc.crypto.falcon.FalconPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.frodo.FrodoPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.hqc.HQCPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.mldsa.MLDSAPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.mldsa.MLDSAPublicKeyParameters;
import org.bouncycastle.pqc.crypto.mlkem.MLKEMPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.newhope.NHPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.ntru.NTRUPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.ntruprime.NTRULPRimePrivateKeyParameters;
import org.bouncycastle.pqc.crypto.ntruprime.SNTRUPrimePrivateKeyParameters;
import org.bouncycastle.pqc.legacy.picnic.PicnicPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.saber.SABERPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.slhdsa.SLHDSAPrivateKeyParameters;
import org.bouncycastle.pqc.crypto.sphincs.SPHINCSPrivateKeyParameters;
import org.bouncycastle.pqc.legacy.sphincsplus.SPHINCSPlusPrivateKeyParameters;
import org.bouncycastle.util.Pack;

/**
 * Factory to create ASN.1 private key info objects from lightweight private keys.
 */
public class PrivateKeyInfoFactory
{
    private PrivateKeyInfoFactory()
    {
    }

    /**
     * Create a PrivateKeyInfo representation of a private key.
     *
     * @param privateKey the key to be encoded into the info object.
     * @return the appropriate PrivateKeyInfo
     * @throws java.io.IOException on an error encoding the key
     */
    public static PrivateKeyInfo createPrivateKeyInfo(AsymmetricKeyParameter privateKey)
        throws IOException
    {
        return createPrivateKeyInfo(privateKey, null);
    }

    /**
     * Create a PrivateKeyInfo representation of a private key with attributes.
     *
     * @param privateKey the key to be encoded into the info object.
     * @param attributes the set of attributes to be included.
     * @return the appropriate PrivateKeyInfo
     * @throws java.io.IOException on an error encoding the key
     */
    public static PrivateKeyInfo createPrivateKeyInfo(AsymmetricKeyParameter privateKey, ASN1Set attributes)
        throws IOException
    {
        if (privateKey instanceof SPHINCSPrivateKeyParameters)
        {
            SPHINCSPrivateKeyParameters params = (SPHINCSPrivateKeyParameters)privateKey;
            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(PQCObjectIdentifiers.sphincs256,
                new SPHINCS256KeyParams(Utils.sphincs256LookupTreeAlgID(params.getTreeDigest())));

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(params.getKeyData()));
        }
        else if (privateKey instanceof NHPrivateKeyParameters)
        {
            NHPrivateKeyParameters params = (NHPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(PQCObjectIdentifiers.newHope);

            short[] privateKeyData = params.getSecData();

            byte[] octets = new byte[privateKeyData.length * 2];
            for (int i = 0; i != privateKeyData.length; i++)
            {
                Pack.shortToLittleEndian(privateKeyData[i], octets, i * 2);
            }

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(octets));
        }
        else if (privateKey instanceof SPHINCSPlusPrivateKeyParameters)
        {
            SPHINCSPlusPrivateKeyParameters params = (SPHINCSPlusPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.sphincsPlusOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(params.getEncoded()), attributes, params.getPublicKey());
        }
        else if (privateKey instanceof SLHDSAPrivateKeyParameters)
        {
            SLHDSAPrivateKeyParameters params = (SLHDSAPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.slhdsaOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, params.getEncoded(), attributes);
        }
        else if (privateKey instanceof PicnicPrivateKeyParameters)
        {
            PicnicPrivateKeyParameters params = (PicnicPrivateKeyParameters)privateKey;

            byte[] encoding = params.getEncoded();

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.picnicOidLookup(params.getParameters()));
            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else if (privateKey instanceof CMCEPrivateKeyParameters)
        {
            CMCEPrivateKeyParameters params = (CMCEPrivateKeyParameters)privateKey;

            //todo either make CMCEPrivateKey split the parameters from the private key or
            // (current) Make CMCEPrivateKey take parts of the private key splitted in the params

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.mcElieceOidLookup(params.getParameters()));

            CMCEPublicKey cmcePub = new CMCEPublicKey(params.reconstructPublicKey());
            CMCEPrivateKey cmcePriv = new CMCEPrivateKey(0, params.getDelta(), params.getC(), params.getG(), params.getAlpha(), params.getS(), cmcePub);
            return new PrivateKeyInfo(algorithmIdentifier, cmcePriv, attributes);
        }
        else if (privateKey instanceof FrodoPrivateKeyParameters)
        {
            FrodoPrivateKeyParameters params = (FrodoPrivateKeyParameters)privateKey;

            byte[] encoding = params.getEncoded();

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.frodoOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else if (privateKey instanceof SABERPrivateKeyParameters)
        {
            SABERPrivateKeyParameters params = (SABERPrivateKeyParameters)privateKey;

            byte[] encoding = params.getEncoded();

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.saberOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else if (privateKey instanceof NTRUPrivateKeyParameters)
        {
            NTRUPrivateKeyParameters params = (NTRUPrivateKeyParameters)privateKey;

            byte[] encoding = params.getEncoded();

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.ntruOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else if (privateKey instanceof FalconPrivateKeyParameters)
        {
            FalconPrivateKeyParameters params = (FalconPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.falconOidLookup(params.getParameters()));

            FalconPublicKey falconPub = new FalconPublicKey(params.getPublicKey());
            FalconPrivateKey falconPriv = new FalconPrivateKey(0, params.getSpolyf(), params.getG(), params.getSpolyF(), falconPub);

            return new PrivateKeyInfo(algorithmIdentifier, falconPriv, attributes);
        }
        else if (privateKey instanceof MLKEMPrivateKeyParameters)
        {
            MLKEMPrivateKeyParameters params = (MLKEMPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.mlkemOidLookup(params.getParameters()));

            if (params.getPreferredFormat() == MLKEMPrivateKeyParameters.SEED_ONLY)
            {
                return new PrivateKeyInfo(algorithmIdentifier, new DERTaggedObject(false, 0, new DEROctetString(params.getSeed())), attributes);
            }
            else if (params.getPreferredFormat() == MLKEMPrivateKeyParameters.EXPANDED_KEY)
            {
                return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(params.getEncoded()), attributes);
            }
            return new PrivateKeyInfo(algorithmIdentifier, getBasicPQCEncoding(params.getSeed(), params.getEncoded()), attributes);
        }
        else if (privateKey instanceof NTRULPRimePrivateKeyParameters)
        {
            NTRULPRimePrivateKeyParameters params = (NTRULPRimePrivateKeyParameters)privateKey;

            ASN1EncodableVector v = new ASN1EncodableVector();

            v.add(new DEROctetString(params.getEnca()));
            v.add(new DEROctetString(params.getPk()));
            v.add(new DEROctetString(params.getRho()));
            v.add(new DEROctetString(params.getHash()));

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.ntrulprimeOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DERSequence(v), attributes);
        }
        else if (privateKey instanceof SNTRUPrimePrivateKeyParameters)
        {
            SNTRUPrimePrivateKeyParameters params = (SNTRUPrimePrivateKeyParameters)privateKey;

            ASN1EncodableVector v = new ASN1EncodableVector();

            v.add(new DEROctetString(params.getF()));
            v.add(new DEROctetString(params.getGinv()));
            v.add(new DEROctetString(params.getPk()));
            v.add(new DEROctetString(params.getRho()));
            v.add(new DEROctetString(params.getHash()));

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.sntruprimeOidLookup(params.getParameters()));

            return new PrivateKeyInfo(algorithmIdentifier, new DERSequence(v), attributes);
        }
        else if (privateKey instanceof MLDSAPrivateKeyParameters)
        {
            MLDSAPrivateKeyParameters params = (MLDSAPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.mldsaOidLookup(params.getParameters()));

            if (params.getPreferredFormat() == MLDSAPrivateKeyParameters.SEED_ONLY)
            {
                return new PrivateKeyInfo(algorithmIdentifier, new DERTaggedObject(false, 0, new DEROctetString(params.getSeed())), attributes);
            }
            else if (params.getPreferredFormat() == MLDSAPrivateKeyParameters.EXPANDED_KEY)
            {
                return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(params.getEncoded()), attributes);
            }
            return new PrivateKeyInfo(algorithmIdentifier, getBasicPQCEncoding(params.getSeed(), params.getEncoded()), attributes);
        }
        else if (privateKey instanceof DilithiumPrivateKeyParameters)
        {
            DilithiumPrivateKeyParameters params = (DilithiumPrivateKeyParameters)privateKey;

            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.dilithiumOidLookup(params.getParameters()));

            DilithiumPublicKeyParameters pubParams = params.getPublicKeyParameters();

            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(params.getEncoded()), attributes, pubParams.getEncoded());
        }
        else if (privateKey instanceof BIKEPrivateKeyParameters)
        {
            BIKEPrivateKeyParameters params = (BIKEPrivateKeyParameters)privateKey;
            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.bikeOidLookup(params.getParameters()));
            byte[] encoding = params.getEncoded();
            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else if (privateKey instanceof HQCPrivateKeyParameters)
        {
            HQCPrivateKeyParameters params = (HQCPrivateKeyParameters)privateKey;
            AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(Utils.hqcOidLookup(params.getParameters()));
            byte[] encoding = params.getEncoded();
            return new PrivateKeyInfo(algorithmIdentifier, new DEROctetString(encoding), attributes);
        }
        else
        {
            throw new IOException("key parameters not recognized");
        }
    }

    private static ASN1Sequence getBasicPQCEncoding(byte[] seed, byte[] expanded)
    {
        ASN1EncodableVector v = new ASN1EncodableVector(2);

        v.add(new DEROctetString(seed));

        v.add(new DEROctetString(expanded));

        return new DERSequence(v);
    }
}
